The project, which began in November 2011 after years of planning, is 52 percent complete and recently passed a key milestone with the opening of the new school gymnasium, housed in a new 16,960-square-foot addition attached to the main complex.

Except for a three-story addition built in 1975, the current project marks the only major facility upgrade on the campus since the vocational school opened its doors nearly a half-century ago.

The district serves approximately 1,250 high school students from Brockton, East Bridgewater, Easton, Foxborough, Mansfield, Norton, Sharon, Stoughton, and West Bridgewater. It also has a separate program serving about 120 post-secondary students.

“It’s very exciting,” said Joe Dutcher, of East Bridgewater, who chairs the district building committee and is a member of the regional school committee.

Dutcher said he is impressed by how well the school prepares its students for college and vocations. But he said the physical improvements now being undertaken “will make them even more competitive in the workforce.”

In addition to the gymnasium addition, the project — 80 percent of whose eligible costs are being borne by the state — involves updating plumbing, electrical, and heating systems, installing air conditioning and sprinkler systems, replacing windows with more energy-efficient ones, and measures to improve handicapped access.

The work also includes construction of a new media center, science labs, and a student common area with an expanded cafeteria that will also serve as an auditorium.

Renovations are also being carried out and new modern equipment installed in program areas, and space is being outfitted for two new high school vocational programs — dental assistant and medical assistant — according to School Superintendent Luis Lopes.

Small improvements are also being carried out to some of the campus’s other facilities, including the conversion of an old electrical building to a new early education center and handicapped-access upgrades.

Barry Chin/Globe Staff

Southeastern Regional Vocational Technical High School Superintendent Luis Lopes in the school’s new dental area.

Opened in 1965, Southeastern offers 22 majors to its high school students covering the fields of transportation and metalworking; health and public services; building and design; visual and performing arts; and emerging technologies. It offers four programs for its post-secondary students.

With the exception of the 1975 addition, the eight buildings forming the approximately 280,000-square-foot core complex date to the school’s original construction.

Lopes said an added plus to the project is that it has not required any additional charges to the district or any local tax increases.

The Massachusetts School Building Authority is covering about $26 million of the costs. Lopes said the district is funding its approximately $7 million share through a $6.2 million bond, and available revenues and savings. Because it is able to repay the bond through existing annual capital assessments to its member communities, Southeastern did not have to ask them for any additional money.

Lopes said the school has been well maintained over the years, thanks in part to the many projects building trade students have carried out under faculty supervision. But “from a facilities standpoint, it was tired,” he said of the core complex, citing for example the aging mechanical systems and windows.

He said modernizing of the building’s spaces and equipment will also enhance learning. “The new science labs are going to support our academic program, and nearly every vocational program is getting a face lift to address the new technologies,” he said.

“Programs change and evolve over time,” Lopes said. He noted as an example, “what was being taught in a machine shop in the ’60s and ’70s is now advanced manufacturing with [computerized numerical control] machines. So it requires some upgrades.”

Barry Chin/Globe Staff)

A construction worker inside the school's old gymnasium, which will become a new media center.

“I’m thrilled. It will change the culture of our building,” David Wheeler, Southeastern’s high school principal, said of the upgrades. “I can already see kids right now so happy to be here.”

Lopes said an additional benefit of the project is the ability to add two new majors to the educational offerings.

Unlike many previous building projects at the school, students have limited involvement in the current construction. But officials said the project has been a valuable educational tool, providing teachers an opportunity to demonstrate construction techniques to their classes.

Lopes said teachers and students on occasion are also able to lend a hand to help contractors respond to minor issues that arise, such as restoring electricity to a room that has lost power.

“It’s one of those nice things about being in a vocational school. You can address those issues,” he said.

Students, overseen by teachers, are also carrying out some tasks that complement the project, such as building display cases in the new gym, custom seating areas in the student common, and a new circulation desk in the media center, according to Lopes, who estimates the school is saving $2 million from the free student labor.

The project is scheduled for completion in January 2014, but officials are hoping work might be done as early as September.